It is known in the prior art that aqueous systems, particularly industrial aqueous systems such as boiler systems, heat exchangers, cooling towers, desalinization equipment, etc., are subject to the accumulation and deposition of solid particles on the internal surfaces of the equipment and pipes. Such deposits are undesirable since they greatly retard the transfer of heat by limiting or reducing the circulation of water and by insulating the surface of the equipment which the circulating water is intended to cool. In addition, serious corrosion may occur on the equipment surfaces below such deposits.
Among the various undesirable deposits that may form and accumulate in aqueous systems are deposits of insoluble iron compounds that are derived from soluble iron which is present in the system. The deposition of iron oxide is of particular concern in today's boiler water treatment programs. It is believed that much of the iron oxide precipitates are comprised of ferric oxide and ferric hydroxide, wherein the iron is in its oxidation state of three. For purposes of this invention, iron oxide precipitates are hereinafter referred to as iron (III) oxide.
The control or elimination of iron (III) oxide deposits is commonly effected by the addition of chelants, or chelant/polymer treatments. However, chelants are known to be corrosive, and the excess overfeed of chelants has been known to dissolve and remove large quantities of iron oxides. This is undesirable since the chelant does not distinguish between the objectionable iron oxide deposits and the protective film of magnetite (Fe.sub.3 O.sub.4 --the oxide formed under boiler conditions).
Both catechol and hydroquinone are commercially available materials which have heretofore been used in boiler systems as oxygen scavengers. It was surprising and unexpected that these compounds would also provide effective iron (III) oxide dispersing abilities in aqueous systems, particularly since other dihydroxybenzene compounds, such as for example, resorcinol, were not effective at all in dispersing iron (III) oxide.